Centrifugal blowers or pumps



0d. 9, 1956 A. BUCHI 2,765,748

CENTRIF'UGAL 'BLOWERS 0R PUMPS Filed April 13, 1953 4 Sheets-Sheet 1 0a. 9, 1956 v A. BUCHI 2,765,748

CENTRIFUGAL BLOWERS OR PUMPS Filed April- 1-3, 1953 4 Sheets-Sheet 2 @ct. g, 1956 A. BUCHI 2,735,748

CENTRIFUGAL. BLOWERS OR PUMPS Filed April 13, 195 4 Sheets-Sheet s Oct. 9, 1956 A. BUCHI 2,765,748

CENTRIFUGAL BLOWERS 0R PUMPS Filed April 13, 1953 4 Sheets-Sheet 4 This invention relates to centrifugal blowers or pumps, comprising in at least two separate housing sections a guide flow device including receiving and difiusor passages surrounding the rotor to receive the pressure medium from the rotor blading and to discharge the pressure medium into at least one laterally offset space.

The main object of the invention is to provide for a construction of the blower housing consisting of separate housing sections in which the guide passages for the guide flow device are formed by open recesses; the walls of the recesses of the assembled housing sections being aligned to form said guide passages, and said walls having no undercut portions, so that for casting the housing sections the moulds therefore can be formed by the use of solid patterns avoiding any use of destructible cores, or in that the housing sections can be cast directly by means of metal moulds, according to the chill casting process, or also by pressing same with press-tools.

The features of the present invention are shown in the accompanying drawings comprising Figs. 1 to 10 which show two different constructional embodiments. Similar parts or parts performing similar functions are marked with the same numerals, or letters.

Figs. 1, la and 2 show by way of example embodiments of a single-stage centrifugal blower.

Figs. 3 and 4 show an example of a multi-stage centrifugal blower.

Figs. 5 and 6 show in axial section the casting forms or moulds for casting a housing section A or B.

Figs. 7 and 8 show the housing sections produced according to Figs. 5 and 6.

Fig. 9 shows a detail of a particular section of the casting form or mould shown in Fig. 6, seen in development.

Fig. 10 is a development of the housing section shown in Fig. 9.

In Fig. 1 there is shown on the line I-I of Fig. 2 a section through the axis of a single-stage centrifugal blower with the rotor wheel 1 and the driving shaft 2. The operating medium flows through the inlet opening 3 towards the rotor wheel and after leaving the latter it flows into the gap space 4 surrounding the rotor wheel.

Fig. 2 is a view of Fig. 1 on the line II-II of Fig. l. Outwardly of the gap space are arranged eight collecting passages 5 which transfer operating medium into the rectilinear diffusers 6. The operating medium passes from these diffusers 6 into the difiuser passages 7 which are curved in the axial direction.

Referring to Figs. 1 and 2 the blower comprises housing sections A, B, C and D which are separated one from the other in planes normal to the machine axis. The guide passages for the medium are formed in these housing sections by open recesses without undercut walls. The collecting passages 5 open towards the gap 4 and the rectilinear diffuser passages 6 having a circular cross section, consist of recesses in the housing parts A and B without undercut walls which run one towards the other at the division point tangentially in the horizontal direc- 2,765,748 Patented Oct. 9, 1956 tion and are divided by the division plane into symmetrical halves. In the diffuser passage 7 the initially still circular cross section in the housing section B merges into a cross section which is formed by a recess 7 defined by a right angle and which embodies no under-cut wall sections. This section is further so formed that the advantages of the circular form of such guide passages are retained as much as possible which is permitted by the fact that the curved parts extend nearly to the edges of the division surface. The recess 7 in the housing part A runs in the peripheral direction and is progressively deeper. At the point b1 (Figs. 2 and 10) this reaches a depth which corresponds to the width of the housing section. In the peripheral direction from the point b2 the passage 7, which to this point consists of the recesses 7 and 7 in both housing sections A and B, opens in the collecting space 8 of the housing section C. This difiuser passage section is marked 7". The recess 7" merges thereby in the flow direction tangentially into the recess 7" and guides the pressure medium in the peripheral direction into the collecting space 8. The inlet edge ha of 7" lies in the division plane of the housing sections A and B; at these points the depth of the passage sections 7" opening towards the collecting space 8 is approximately equal to the width of the housing section A. The depth of the recess for the diffuser passage 7 is progressively smaller from the point 122 as far as b3. Between the edges b1 and b2 an opening b is formed through the housing member A. The recesses on both sides of the housing member A are made without undercut walls.

This member can be cast in repeatedly used casting or moulding forms or moulds as shown in Fig. 6. The diffuser passage section 7 which consists of the recess 7" in the housing member B can, as shown in Fig. l, have a section in the form of a circular sector which merges tangentially into the recess in the housing section B. The recesses in the housing parts, which serve for saving the material used and for reduction of weight, are also formed without undercut walls. A repeatedly usable moulding form or mould corresponding to the housing section B is shown in approximate manner in Fig. 5. Fig. 7 shows the housing section B cast in the forms or moulds of Fig. 5. These forms or moulds are appropriately constructed for casting the housing section according to the chill casting, die casting or spray casting processes.

The collecting space 3 is formed by the spiral housing C and is divided from the housing member A in a plane normal to the machine axis. The collecting space 8 is made by a recess without an undercut wall. In the example shown this arrangement extends as far as the tubular outflow connections C. In a further embodiment, not shown, these outlet connections can also be formed as an open recess without the undercut walls and covered by means of a plate. The inflow D for the pressure medium is made separate from the housing section A and moreover consists of two parts divided in the direction of the machine axis in a diametral plane and provided with flanges for fixing bolts. These parts for the inflow of the pressure medium and for the part of the spiral housing forming the collecting space are also produced by casting with repeatedly usable forms or molds according to one of the aforesaid processes.

Fig. in shows in similar axial section to Fig. 1 a con struction in which the division plane of the housing sections A and C is displaced towards the right in the spiral housing C forming the collecting space 8. it comprises for this reason a housing section A and a housing part C". In this way the outlet connection C in Fig. l is likewise divided into two parts. Each of these parts is constructed as a recess without undecut walls and forms a single part on the one hand with the housing section C and on the other hand with the housing section A.

The construction of the parts A and C" in reference to their division planes is such that also the partial walls forming the collecting space embody no undercut portions so that the housing section A can be produced like A of Fig. 1 with repeatedly usable moulds or forms according to the chill casting, die casting or spray casting processes. The housing section C forms the cover of the collecting space and is formed in reference to the division planes without undercut walls by the same method of production.

Figs. 3 and 4 show an embodiment of multi-stage centrifugal blower. Fig. 3 is an axial section on the line IlIlli of Fig. 4. Fig. 4 is a section on the line IVIV of Fig. 3. The guide device comprises the passages 5, 6 and 7, which could be constructed similarly to the arrangement described in Fig. 1 and reversal passages 9. The diffuser passage '7 is curved in the direction of the machine axis and guides the pressure medium on the other side of the housing part A approximately in the peripheral direction into the reversal passages 9. In these reversal passages the pressure medium is fed to the rotor wheel of the next stage. The guide passages 5, 6and 7 are, in the previous embodiment, formed as open recesses which embody no undercut walls. The reversal passages 9 are also formed as recesses on the other side of the housing section A with reference to the passages formed in the two housing sections A and B, such recesses being formed without undercut walls and are covered in the axial direction by a cover plate 10 which is arranged between the housing section A of the first stage and the housing section B of the second stage. The housing section of the last stage is constructed in approximately the same manner as the housing section A of Fig. 1. The diffuser passages 7 open at a point where they have become progressively deeper as far as the width of the housing section A, at In (see Figs. 2 and 10) on the other side of the housing section A where they are constructed again as open recesses 7" (Fig. 2) without undercut walls and open into the collecting space 8. In this example the housing section C is constructed according to the previously known methods and can be produced only according to the sand casting process with destructible cores. The inlet housing for the pressure medium likewise is formed according to the previously known methods of construction and likewise can only be produced according to the sand casting process. These housing parts can according to the present invention also be constructed so that they can be produced in repeatedly usable forms or moulds according to the chill casting, die casting or spray casting processes.

Figs. 5 and 6 show how according to the present in vention the housing sections A and B can be produced with repeatedly usable casting or moulding forms according to the chill casting, die casting or spray casting processes. are indicated at or and as. The mould inlets will be seen at m, and the risers at at"; a are air vent passages. The shaping of the article to be cast according to Fig. 5 corresponds to one housing section B. Fig. 6 refers to the casting of a housing section A. in Fig. 7 the housing member B and in Fig. 8 the housing section A are shown in axial section as well as these parts withdrawn from the casting mould or form. Fig. 9 shows the form or mould shown in Fig. 6 in section VV of Fig. 4 through a guide passage and seen in development and shows how the parts are cast around the above described aperture 12 and how the forms or moulds are constructed at these points. Fig. 10 shows the construction of the housing section A corresponding to Fig. 9 with the parts around the opening 11.

The casting forms or moulds shown in Figs. 5, 6 and 9 are repeatedly usable and are thus chosen for producing the housing sections described according to the chill casting, die casting or spray casting processes. By the formation of the casting or pressing forms or moulds ac- The casting moulds for one housing section cording to the present invention the possibility is obtained that for each housing section only two such forms or moulds are required however many guide passages, diffusers and reversal passages as well as all the recesses, must thereby be produced. The housing parts so produced are obtained to exactly the correct size and comprise the smooth surfaces necessary for fluid flow machines without further working.

I claim:

1. A centrifugal blower or pump having a bladed rotor and a housing enclosing said rotor, 21 delivery guiding arrangement including a series of guide-duct diffusers extending through said housing and radiating from the rotor periphery, said housing also having a portion forming an axially offset scroll space, each guide duct diffuser comprising a rectilinear front portion and a rear portion, said rear portion being curved towards said scroll space, said housing consisting of at least two parts separated along a plane normal to the rotor axis, said guide-duct diffusers being formed of a surface of a first of said housing parts,

and of an oppositely formed surface of a second of said housing parts, the second housing part lying on the side of said scroll comprising a radial wall defining one side thereof, said curved diffuser portion being axially deflected and passing through said second housing part, the portion of said curved and axially deflected diffuser passing through the second housing part comprising an inflow edge lying in said normal plane separating said two housing parts, an out-flow edge lying on said radial wall of the second. housing part adjoining said scroll and side walls joining the inner and outer ends of said edges, respectively, and the surface of said radial plane for the formation of said curved diffuser within the second housing part, said inflow edge and, said outflow edge being substantially rectilinear, and the construction being such that in axial view said rectilinear edges clear each other fully, and said side walls being directed axially.

2. A centrifugal blower or pump according to claim 1, wherein the second housing part is formed on the side of the scroll space with a portion thereof.

3. A centrifugal blower or pump having a bladed rotor and a housing enclosing said rotor, at delivery guiding arrangement including a series of guide-duct ditfusers extending through said housing and radiating from the rotor periphery, said housing also having a portion forming an axially offset scroll space, each guide duct diffuser comprising arectilinear front portion and a rear portion, said rear portion being curved towards said scroll space, said housing consisting of at least two parts separated along a plane normal to the rotor axis, said guide-duct diffusers being formed of a surface of a first of said housing parts, and of an oppositely formed surface of a second of said housing parts, the second housing part lying on the side of said scroll comprising a radial wall defining one side thereof, said curved difiuser portion being axially deflected and passing through said second housing part, the portion of said curved and axially deflected dilfuser passing through the second housing part comprising an inflow edge lying in said normal plane separating said two housing parts, an outflow edge lying on said radial Wall of the second housing part adjoining said scroll and side walls joining the inner and outer ends of said edges, respectively, and the surface of said radial plane for the formation of said curved diffuser within the second housing part, said inflow edge and said outflow edge being substantially rectilinear, and the construction being such that in axial view said rectilinear edges clear each other fully, and said side walls being directed perpendicular to said normal plane separating the two housing parts.

References Cited in the file of this patent UNITED STATES PATENTS 2,311,024 Buchi Feb. 16, 1943 

